Method of heat recuperation.



H. L. DOHERTY. Mum OF HEAT RECUPERATION.

APPLICATION FILED JAN-17,1911. '*l 15Qj,838, Patented Aug. 17, 1915.

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' METHOD OF HEAT RECUPE N.

APPLICATION HLEDJAN. l7,

1,150,838. I Patented Aug. 17, 1915.

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Henry L.Duherty, Swwwtm his W Z4444 HENRY L. DOHERTY, on NEW YORKJN. Y.

METHOD OF HEAT RECUPERATION.

Specification of Letters Patent.

Application filed January 17, 1911. Serial mi 603,0 89.

To altflwhom it may concern:

'Be it known. that I, HENRY L. DOHERTY,

atitizen of the United States, and a 'resident of New York city, in the county of New York and State of New York, have inventedcertain new and useful Improvements in Methods of Heat Recuperation, of

which thefollowing is a specification.

' My invention relates to a mthod of heat recuperationand, in particular-,to a method of securing heat IBCUPGIZLUOII' 1n producergas-fired furnaces by balancing the total heat capacities of the incoming and outgoing draft currents of the furnace.

The object of my invention is to provide a method of operating a producer-gas-fired fuiiiaceandits, cooperating gas-prod whereby I am enabledto increase the heat carrying capacity of theair and producer gas. supplied to the furnace sufliciently to permit of the same taking up approximately all of the sensible heat of'fitge combustion gases discharging from the v, rnace.

This invention comprises a method of op- .erating an apparatus of the-character mentioned in which I divide the products of combustion discharging from the furnace into three streams, passing one stream through a recuperator to heat? the producer gas, a second stream through'f-a recuperator to heat the air supplied to the furnace, the first stream, after passing'thrqugh the producer-gas recuperator, beingadyantageously joined to the second stream at" a point in' the air recuperator where the two are at approximately the same temperature, and passing thethird stream through the fuel bed of the producer, whereby part of the sensible heat of the third stream is utilized in sustaining the reduction of part of its carbon dioxid to carbon monoxid by the carbon of the fuel, the temperature of the undissociated carbon-dioxid and nitrogen of the third current and the carbon monoxid formed by the dissociation of part of its carbon dioxid being thereby reduced to a temperature of about 1400 to 1 500 degrees .or to much below the temperature at Which the products of combustion discharge from the furnace. In the accompanying drawings, I have shown a form of apparatus for applying my invention to the operation of a coke-oven and itspradtmer.

Figure 1 is a vertical longitudinal section through the apparatus on the line A, A A A A", A of Fig; 2. Fig. 2 is a vertical. cross-section of one half of the apparatus on the line B, B B B B B of"Fig. 1. Fig. 3 is a vertical cross-section of the other half of the apparatus on the line C, C C G of Fig. 1. Fig. 4 isa similar section on the line D, D D D D*, D, D, D of Fig. 1. Fig. 5 is a similar section of the other half on the line .13], E of Fig. 1. F 6 is a horizontal cross-section 'on the line F, F of Fig; 1.

1, is thecarbonizing chamber of the oven Patented Aug. 1'7, 1915.

the gas producer, 3 the air recuperator, 4

the gas recuperator.

5 is themain combustion gas flue conducting away. the flue'gases from a battery of ovens. I y 6 .6 6 6, etc., are the combustion flues of the oven .on one side. and 7 7 7 7*, etc., are the combustion flues of the other side of the oven.

8 and 8 are the gas up-take flues for the means for regulating the flow of gas through the gas nostrils, and dampers 15 and 15 a means for regulating the flow of air through the air nostrils;

The oven is symmetrical in all respects in relation to a vertical plane through its middle, so that the reproduction ofboth sides of the oven in the several views is unnecessary to'a clear showing of its construction, but numerals referring to the duplicate parts are introduced, herein, for the sake of brev ity and clearness in the description.

1 6 and 16 are flues through which combustion gases are drawn down from the flues (S and 7 under the action of the injectors l7 and 17, respectively, and forced under the grate of the producer 2.

8 with the combustion, 1

18 and 18 are the side walls of the oven and 19 and 19 the end walls.

20 is the feed chute of the gas producer 2. 21, the ash door giving access to the ash pit 21 and the grate 21" of'the producer.

22 are the hand holes, having oevers 23, which provide access to the gas nostrils 10 and dampers 14.

24 and 25 are, respectively, the hand holes and covers of the air nostrils.

The air recuperator 3 comprisesa series of flues, 26, 26, 26, 26, 26 connected two in parallel, so that the gas current passing through them is divided between two flues.

The flues 26, in the form of recuperator shown, are built up from the arch 27 within the vertical flues 28, 28, and are spaced by thespacers 29. The ends of the flues 28, 28, are closed by the special tiles 30 which are made to exactly fit the exterior of the fines 26. There are thus formed two chambers into which the ends of the flues 26 open. Horizontal partitions, 31, divide the chamber thus left in the front of the oven into three sections, 32, 33 and 34, which form the return connectionsfor the flues 26, dividing them, in effect, into a return-bend flue composed of two parallel sections. The horizontal partition 35 forms the return connection 36 for the upper flues of the recuperator at the rear. The partition or arch 37 forms the return-connections 38 and 39 at the rear of the recuperator. Connecting with 38 is the passage 40, through which the products of combustion which have passed through the gas recuperator 4, enter the chamber 38 and join the flue gases which have passed through the upper part of the air recuperator, the combined currents passing thence through the lower two divisions of the lines 26 of the air recuperator, and

through 39 into the flue 41 leading to the main combustion gas flue 5. A tile, 42, serves as a damper to the passage 41. The air enters the recuperator through the inlet passage 43 and passes back through the flue 44, whence it passes through the ports 45 into the main air flue 28. The air discharges from the flues 28 through the ports 46 into the air flue46, thence into the air up-takeflues 9 and 9 respectively, from which it passes through the respective nostrils, 11 11, 11 and 13 13, 13, into the respective 1 combustion flues 6 and 7.

Theconstruction of the producer gas recuperator is similar, in principle, to that of the air recuperator. Horizontal flues, 47, 47*, provide a path for the passage of combustion gas through the recuperator. These flues 47 are built up from the producer arch 48, within the gas' flue 51, being separated by the spacers 49. Tiles, 50, prevent communication between the forward ends of the flues 47 and the producer gas flue 51. The chamber 52 forms a return-connection benication between the inlet ends of the flues 47 and the lower combustion flue 6 A. tile, 67, serves to regulate the flow of combustion gas-from the flue 6 to the upper set of ilues 47. Nostrils, 56, provide passage for the producer gas from producer 2 to the gas flue 51. A passage, 57, establishes commu nication between the g'as flue 51 and the flue 66 connecting with thegas up-take flue 8. Hand-holes 58, with covers 59, provide means of access to the flues 47 of recuperater 4. Hand-holes 60, with covers 61, provide a means of access to the fiues 26.

The method of operating is as follows: A bed of ignited fuel having been built up'in the producer 2 in the manner well known to are partially opened, admitting air to the j. flues 6 and 7 and the gas ignited by the insertion of a red hotiron rod or by a lighted torch through the upper hand-holes 24.

Sufiicient air is admitted through the nostrils l1 and 18 to not only burn all of the gas, which is admitted through the gas nostrils 10 and 12 but to leave an excess of air in the gases filling the flues 6 and 7 At the gas nostrils or ports 10 and'12 more gas is. admitted, the quantity being suflicient to combine with the excess of air mentioned,

the temperature of the gas mixture'being above ignition temperature, and to leave an excess of gas in the gases flowing through flues 6 7 At the air nostrils 11 13 a further excess of air is admitted which burns the previous excess of gas which is present in the mixture as it discharges from the flues 6 and 7 3 into the flues 6* and 7. Further portions of gasand a'irare added to the'current of combustion gases passing through the combustion flues at the nostrils 10 -12 and 1113, respectively. The volume of air admitted through the lower air nostrils 1113 is to be restricted to that quantity which is required to secure complete combustion of the producer gas. Owing to the fact that the air admitted through the lower air ports is, of course, greatly diluted by the gases from the preceding combustions, a very considerable excess is required to prevent an unduly prolonged combustion taking place in flues 67 and 6 7 7 of the residuum of the gas admitted through the gas nostrils i0 12 The gases should discharge from the lower, combustion fines (6-7) completely burned. The volumes of gas entering the combustion flues through the several nos have designated 26*.

trils 10 and 13 are regulated so that a fairly uniform temperature is maintained throughout the lengths of the flues 6 and 7.

My invention relates, essentially, to the disposition which I make of the combustion gases from this point on. The method of ,case of the combustion gases from the flue '6 one current is taken down through the passage ol and passes through the flues 47 of the producer gas recuperator 4. A damper- 67, in connection with other dampers, to be described later, regulates the proportion of the total combustion gases in 6, which is permitted to pass into the fiues 17. A second portion of the combustion gases passes through the length of flue 6 and thence down through the passage 32 into the upper two, parallel flues, 26, whi'ch'I Passing through the flues 26 the combustion gases of this second current enter the fiues 26" and flow through these fiues to the chamber 33, forward again through the flues 26 to chamber 38. The first current flows through the fiues 47*. and 47* of the producer gas recuperator, into the passage 40, through 40 into the chamber 38 where it joins the second current from the fines 26. The combined first and second currents from 38 pass through the flues 26- into the chamber 3 1, thence through the flues 26 and passages 39 and 41 into the .main smoke flue 5 leading to the chimney. A movable tile, 42, serves as a damper to regulate the flow of gases from 39 to the chimney flue 5. The-third current of combustion gases, under the intluence of injector 17, is drawn down through the flue 16,

' openingout of at the combustion gas inlet of same, and is forced by the injector through the ports (34 into the ash-pit 21 of producer 2. The injector 17 is actuated by air under pressure which enters through the pipe 63. The injector 17 should be of some eflicient type that will permit of a large volume of "combustion gases being drawn down through the flue 16 relative to the volume of air introduced through the nozzle (34. The miXture of air and products of combustion passes up through the grate "-21", and into the bed of ignited fuel. there- "on. The combustion gases drawn down through 16 are, initially, at a comparatively high temperature, say, 2000 to 2200 Fah. The combustion gases, in admixture with the air, pass up through the incandescent fuel, the carbon dioxid of the-same reacting with the carbon of the fuel according to the reaction (a) CO PC:2CO, This reaction causes an absorption, under the conditlons obtaining of about 6123 B. T. U.

per pound of carbon of the fuel reacting,

If the combustion gases were entered alone into the fuel bed'the sensible heat ofthe gasesassuming that-they are ente-redinto the fuel bedat 2000w'ould supply," above if the temperature of the fuelbed '(which'r'nay be taken as' 1400 degrees), about 1941B.

T. U. per pound of carbon of the fuel com-- bining with the C0,,- f-the combustion gases. If we assume that the combustion gases carry about 2.1% by welght of free 0,

the combustion of this 0 would render available about 874 B. T. U. above 1400.- The total available heat furnished by the this gas bearing the 00 which is dissociated by reaction (a) would be about 1941 1 87 7 :2818

B. T. U. This would leave a deficiency of about 3305 B. T. U. that must be'supp'lied to the fuel bed in some wa "to insure the maintenance of reaction (a 9 Usually, this deficiency is made up the 'heat developed by. the combustion of part of the fuel in the producer by the airsupplied with the combustion gas, according to the' reaction (b)' (la-0:00. Since the heat rendered available to reaction. (a) by the combustion of 1 lb. of carbonby reaction (b) :about 2217 B. T. U., 'the weight of carbonthat must be burned by reaction (b),- to supply the deficitjn heat by (a), would be 3-3 Now, according to my invention, instead of makingup the deficit in heat of the combustion gases almost entirely by reaction (b), I' make upa material portion of this deficit by supplying to the fuel bed a greater volume of combustion gas from the combustion fines of the apparatus than can be diss ciated by the fuel in the producer.

rent that ----=23.3 lb. of combustion or 142 flue gas could be passed through the fuel bed with its CO, undissociated per pound of carbon reacting according to reaction (a), the reaction could theoretically be maintained without the use of any primary air. Such a method of operation, however, would produce a very Weak producer gas, since the proportion of flue gas that would be theoretically required would be nearly double the proportion that would be requircd to furnish the (X), for reaction (a)the ,latter requirement being about 13.7 lb. of a flue gas containing an excess of 2.1% of free 0, which is about the smallest working excess practicable. Therefore, in carrying out my invention, I do not aim to carry on the gas making operation Without any primary air, but, to limit the pro- .portion of air introduced into the producer to the smallest practicable amount permissible under tlie method of operationdescribed. This, in practice, will be the volume of air that must be used in the 1n ector 17 to divert the portion of the combustion products going to the producer from fiues (S and 7 through the flues 16 and 16 to the ash pit of the producer. The volume so required will vary with the pressure of the air, the shape ofthe air and receiving nozzle, size of suction ducts, etc. Therefore, I cannot prescribe any exact proportion between the primary air and flue gas, other than that I restrict the air to the lowest practicable volume in'any case.

It is to be noted that, by this method of operating my. producer, I affect materially 'the recuperation of heat from thecombusto said furnace, in transferring part of the sensible vheat of another portion of said combustion gases to preheated air, and transferring the major portion of the re- ..maining sensible heat of both of said curtion products. In the first place, the carbon monoxid produced per ton of fuel consumed on the grate, is much greater than when the producer is run in the usual way. such of the C0, of the combustion gases as reacts with the fuel onthe grate, produces double its own volume of carbon nionoxid having a thermal capacity of about 1.46

I 7 times the thermal capacity of the CO, distion of the (JO of the gases that the fuel bed will dissociate under the conditions of operation obtaining. My aim is to, as

nearly as practicable, equalize the'heat capacities of the gaseous currentsflowing to Since the combustionflues, and the products of, combustion discharging from the fines. By as much as I can approach this condition,

just so much do I approach the realization of the conditions that make the perfect recuperation of theheat. of the waste products of a furnace practicable.

Having described my invention, what I claim is:

1. The method of recuperating the heat of the combustion gases from a gas-fired furnace which comprises transferring a part of the sensible heat of one portion of said combustion gases to heat the gas supplied rents of combustion gases to air, to preheat the same.

2. The method of recuperating the heat of the combustion gases from a gas-fired furnace which comprises passing one portion of said combustion gases through a gas recuperator to raise the temperature of the gas.

supplied to said furnace, passing-another portion of said combustion gases through an air recuperator to heat the air supplied to said furnace, and mingling the first of said portions of combustion gases after it has passed through the said gas recuperator with the second of said portions of combus tion gases at such place in the said air recuperator at which the two portions approximate in temperature.

The method of recuperating the heat of the combustion gases from agas-fired furnace, which comprises passing one portion of said combustion gases through the fuel bed of the gas producer of said furnace, passing a second portion of said combustion gases through a producer gas recuperator to raise the temperature of the producer gas from said gas producer, passing a third por-.

tion of combustion gases through an air recuperator to heat the air supplied to said furnace, and adding the said second portion of combustion gases, after they have passed through said producer gas recuperator, to the said third portion of combustion gases at an intermediate region of said air recuperator.

at. The method of recuperating the heat of the combustion gases from a gassfired fur- ;iiace, which comprises dividing the said gases into three streams, passing the first of said streams through the fuel bed of a gas producer, passing thesecond of said streams through a producer gas recuperator .to raise the temperature of the producer gas before the latter is introduced intosaid furnac'e,v passing the third of said streams through an air recuperator to heat the air supplied to said furnace and in ininglingthe said second streaim, after the same has been used to heat the said producer gas, with the said third stream of combustion gases at such a place in the saidair recuperator as the temperature of the said. thirdjstream passing therethroi'igh approximates to the teiiiperatureof the said second stream.

5. The process of recuperating heat of combustion gases from a, producer-gas-fired furnace, wh ch comprises passiii'ga portion of said combustion gases in adiiiixtu ewith a minimum volume of .airth'rough the fuel bed of the. gas producer of, said furnace to generate CO, in part by reaction'ofa portion of the CO of said portion of combustion gases and in part by the reaction of the O of the air with carbon of said fuel bed, the volume of said portion of combustion gases being materially greater than that corresponding to the CO which said fuel bed is capable of reducing under the conditions obtaining therein, the heat for the reduction of that portion of theCO reacting with the carbon of said fuel bed being supplied in part by the sensible heat of the said portion of combustion gases, and in part by heat developed by the reaction of the of said air with said 'fuel bed, transferring heat from another portion of said combustion gases to the gases discharging from said fuel bed, passing a third portion of combustion gases throughan air recuperator to heat air, and adding the said second portion of combustion gases, after they have been used to heat the said gases from said vfuel bed, to the said third portion of comheat-carrying capacity of the draft-current supplied to said furnace by passing one portion of said combustion gases in admixture with aiinthrough the fuel bed of the gas producer of said furnace, whereby a part of the carbon dioxid of said combustlon gases ls converted into carbon IIlOIlOXld.

and a further volume of carbon monoxid is formed by reaction between the oxygen of said air and said incandescent carbon, passing a second .portion of said combustion gases through a producer gas recuperator to raise the temperature of the producer ga s,

generated in said producer, passing a third stream of combustion gases through an air recuperator to heat the an supplied to sald furnace, and adding the said second stream of combustion gases, after the same has passed through the said producer gas recuperator, to the said third stream at that level in the said air recuperator at which the said third stream approximates to the temperature of said second stream.

' Signed at New York cityin the county of New York and State of New York this 16th day of January A. D. 1911.

HENRY L. DOHERTY.

Witnesses:

J. M. McMILLIN, FRANK BLACKBURN. 

